Sound Level Combiner
The sound-level combiner adds independent sound sources logarithmically to estimate their combined sound-pressure level in decibels.
How to use this calculator
- Enter two sound levels in dB and optionally a third; leave the optional field blank to omit it.
- Check the units and definitions before comparing results with another source.
- Change one input at a time when comparing scenarios, and keep the reporting period and assumptions consistent.
Formula used by the sound level combiner calculator
Ltotal = 10 log₁₀(Σ 10^(Li/10))
- Ltotal = 10 log₁₀(Σ 10^(Li/10))
- The estimate assumes independent sources and comparable measurements. Coherent sources, distance, room acoustics, weighting and measurement conditions can change a real reading.
- Inputs are checked for required values and valid ranges; displayed results are rounded for readability.
Worked examples
Worked example
Two independent sources each measure 60 dB.
Their combined level is 10 log₁₀(10⁶ + 10⁶) ≈ 63.01 dB.
Their combined level is 10 log₁₀(10⁶ + 10⁶) ≈ 63.01 dB.
Understanding the result
The sound-level combiner adds independent sound sources logarithmically to estimate their combined sound-pressure level in decibels.
The estimate assumes independent sources and comparable measurements. Coherent sources, distance, room acoustics, weighting and measurement conditions can change a real reading.
Important notes
The estimate assumes independent sources and comparable measurements. Coherent sources, distance, room acoustics, weighting and measurement conditions can change a real reading.
The result applies to the numbers and assumptions entered here; verify specifications for safety-critical or regulated uses.
Frequently asked questions
Why do two 60 dB sources not equal 120 dB?
Decibels are logarithmic, so sound power contributions must be combined before converting back to the dB scale.
Does this predict the level anywhere in a room?
No. It combines levels measured under comparable conditions and does not model distance or room acoustics.
How do I use this calculator?
Enter two sound levels in dB and optionally a third; leave the optional field blank to omit it.
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This page provides a calculation tool plus explanatory information so you can understand what the result means and when the underlying method may not fit your situation.